# Customer.io vs Twilio SendGrid Email API Comparison
---
## AI Generated Summary
- **G2 reviewers report** that Customer.io excels in user experience, with many users praising its intuitive navigation and straightforward data flow. This ease of use is complemented by advanced features like AI and automation, which add significant value to the platform.
- **Users say** that Twilio SendGrid Email API offers a robust solution for startups, highlighting its competitive pricing and easy signup process. Reviewers appreciate the flexibility of using HTTP requests for dynamic templates, making it a versatile choice for developers.
- **According to verified reviews** , Customer.io stands out for its strong support and responsiveness, with users noting that the company frequently releases updates and improvements without pushing customers into enterprise sales funnels. This commitment to customer satisfaction is reflected in its higher G2 Score.
- **Reviewers mention** that Twilio SendGrid Email API provides excellent integration capabilities, particularly with its Logic Apps connectors, which simplify the process of connecting to other services. This feature is particularly beneficial for users looking to streamline their email workflows.
- **G2 reviewers highlight** that while both platforms have similar ease of use scores, Twilio SendGrid Email API has a slight edge in setup ease, making it a favorable option for users who prioritize quick implementation and getting started without hassle.
- **Users report** that Customer.io's focus on AI-driven features and automation tools enhances its overall functionality, making it a preferred choice for businesses looking to leverage advanced marketing strategies. However, some users feel that its pricing may be a barrier for smaller businesses compared to Twilio SendGrid's more accessible pricing structure.



| | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Star Rating** | 4.4 out of 5 | 4.0 out of 5 | 
| **Total Reviews** | 828 | 368 | 
| **Largest Market Segment** | Small-Business (58.5% of reviews) | Small-Business (68.3% of reviews) | 
| **Entry Level Price** | Starting at $100.00 Per Month | $14.95 to $29.95  per month  | 

---
## Top Pros & Cons

### Customer.io

Pros:
- Ease of Use (227 reviews)
- Automation (152 reviews)

Cons:
- Learning Curve (91 reviews)
- Missing Features (78 reviews)

### Twilio SendGrid Email API

Pros:
- Ease of Use (2 reviews)
- Easy Integrations (2 reviews)

Cons:
- Difficult Setup (1 reviews)
- Limited Templates (1 reviews)

---
## Ratings Comparison
| Rating | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
  | **Meets Requirements** | 8.7 (668 reviews) | 8.5 (317 reviews) | 
  | **Ease of Use** | 8.3 (690 reviews) | 8.3 (320 reviews) | 
  | **Ease of Setup** | 8.0 (481 reviews) | 8.2 (182 reviews) | 
  | **Ease of Admin** | 8.6 (279 reviews) | 8.2 (175 reviews) | 
  | **Quality of Support** | 8.6 (596 reviews) | 7.5 (253 reviews) | 
  | **Has the product been a good partner in doing business?** | 9.0 (278 reviews) | 7.8 (164 reviews) | 
  | **Product Direction (% positive)** | 9.1 (661 reviews) | 7.2 (302 reviews) | 

---
## Pricing

### Customer.io

#### Entry-Level Pricing

Plan: Essentials

Price: Starting at $100.00 Per Month

Description: For small companies who are gaining momentum.

Key Features:
- Send emails, push, in-app, SMS, webhooks
-  Track custom events and attributes
- Visual workflow builder

[Browse all 3 editions](https://www.g2.com/products/customer-io/pricing)

#### Free Trial

Yes

### Twilio SendGrid Email API

#### Entry-Level Pricing

Plan: ESSENTIALS (40K, 100K Packages)

Price: $14.95 to $29.95  per month 

Description: Two packages to meet your mail sending needs 

Key Features:
- Easy to Use APIs and Webhooks
- Detailed Analytics and Reporting
- DKIM Customization 

[Browse all 3 editions](https://www.g2.com/products/twilio-sendgrid-email-api/pricing)

#### Free Trial

Yes

---
## Features Comparison By Category

### Marketing Automation

| Product | Score | Reviews |
|---|---|---|
| **Customer.io** | 7.5/10 | 531 |
| **Twilio SendGrid Email API** | N/A | N/A |

#### Email Marketing

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Building and Personalizing Emails** | 8.8 (450 reviews) ✓ Verified | Not enough data | 
| **Sending Outbound Emails** | 8.8 (426 reviews) ✓ Verified | Not enough data | 
| **Manage Email Deliverability** | 8.4 (395 reviews) ✓ Verified | Not enough data | 
| **Automated Email Responses** | 8.4 (389 reviews) ✓ Verified | Not enough data | 

#### Online Marketing

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Landing Pages and Forms** | 6.3 (331 reviews) | Not enough data | 
| **Dynamic Content** | 8.0 (360 reviews) ✓ Verified | Not enough data | 
| **A/B Testing** | 8.3 (385 reviews) ✓ Verified | Not enough data | 
| **Mobile Optimized** | 7.9 (361 reviews) ✓ Verified | Not enough data | 
| **Search Tracking and Optimization** | Feature Not Available | Not enough data | 

#### Lead Management

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Marketing Lead Database** | 7.4 (336 reviews) ✓ Verified | Not enough data | 
| **Data Quality Management** | 7.6 (330 reviews) | Not enough data | 
| **Segmentation** | 8.6 (404 reviews) ✓ Verified | Not enough data | 
| **Lead Scoring and Grading** | 6.8 (310 reviews) | Not enough data | 
| **Lead Nurturing** | 7.7 (337 reviews) ✓ Verified | Not enough data | 
| **Online Behavior Tracking** | 7.3 (334 reviews) ✓ Verified | Not enough data | 
| **Automated Alerts and Tasks** | 7.3 (315 reviews) | Not enough data | 
| **CRM Lead Integration** | 7.3 (323 reviews) ✓ Verified | Not enough data | 

#### Campaign Management

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Program Management** | 7.7 (344 reviews) | Not enough data | 
| **Event / Webinar Marketing** | 7.0 (320 reviews) | Not enough data | 
| **Calendaring** | Feature Not Available | Not enough data | 
| **Budgeting** | Feature Not Available | Not enough data | 

#### Social

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Social Listening** | Feature Not Available | Not enough data | 
| **Social Sharing** | 6.6 (306 reviews) | Not enough data | 
| **Social Campaigns** | Feature Not Available | Not enough data | 
| **Social Media Engagement** | Feature Not Available | Not enough data | 
| **Social Media Advertising** | Feature Not Available | Not enough data | 

#### Reporting & Analytics

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Basic Reporting** | 7.8 (391 reviews) ✓ Verified | Not enough data | 
| **Web Analytics** | 6.9 (332 reviews) ✓ Verified | Not enough data | 
| **ROI Analytics** | 6.5 (321 reviews) | Not enough data | 
| **Revenue Analytics** | 6.3 (310 reviews) | Not enough data | 
| **SEO / Keyword Analytics** | Feature Not Available | Not enough data | 

#### Platform

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Customization ** | 8.3 (379 reviews) ✓ Verified | Not enough data | 
| **Workflow Capability** | 8.5 (395 reviews) ✓ Verified | Not enough data | 
| **User, Role, and Access Management** | 8.5 (358 reviews) ✓ Verified | Not enough data | 
| **Internationalization** | 7.7 (332 reviews) ✓ Verified | Not enough data | 
| **Sandbox / Test Environments** | 7.7 (348 reviews) ✓ Verified | Not enough data | 
| **Performance and Reliability** | 8.7 (378 reviews) ✓ Verified | Not enough data | 
| **Output Document Generation** | 7.2 (313 reviews) ✓ Verified | Not enough data | 

#### Agentic AI - Marketing Automation

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Autonomous Task Execution** | 6.3 (69 reviews) | Not enough data | 
| **Multi-step Planning** | 6.5 (69 reviews) | Not enough data | 
| **Cross-system Integration** | 6.8 (63 reviews) | Not enough data | 
| **Adaptive Learning** | 6.4 (65 reviews) | Not enough data | 
| **Proactive Assistance** | 6.3 (66 reviews) | Not enough data | 
| **Decision Making** | 6.3 (67 reviews) | Not enough data | 

#### Integration

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Data Import & Export Tools** | 8.3 (377 reviews) ✓ Verified | Not enough data | 
| **Integration APIs** | 8.3 (386 reviews) ✓ Verified | Not enough data | 
| **Breadth of Partner Applications** | 7.6 (344 reviews) ✓ Verified | Not enough data | 

### Transactional Email

| Product | Score | Reviews |
|---|---|---|
| **Customer.io** | 8.1/10 | 287 |
| **Twilio SendGrid Email API** | 8.5/10 | 150 |

#### Administration

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Template Creation** | 8.1 (267 reviews) | 7.9 (85 reviews) | 
| **Preset Template Availability** | 7.4 (235 reviews) | 7.5 (77 reviews) | 
| **Custom Unsubscribe** | 8.1 (252 reviews) | 8.1 (84 reviews) | 
| **Email Segmentation** | 8.9 (268 reviews) | 8.1 (89 reviews) | 
| **Detailed Server Logs** | 7.7 (237 reviews) | 7.9 (97 reviews) | 
| **Notifications** | 7.8 (244 reviews) | 8.3 (100 reviews) | 

#### Integrations

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Webhooks** | 8.6 (238 reviews) | 8.9 (91 reviews) | 
| **Event Tracking API** | 8.5 (241 reviews) | 8.8 (84 reviews) | 
| **Mail Send API** | 8.4 (205 reviews) | 9.3 (122 reviews) | 
| **Spam Filter Testing** | 7.2 (178 reviews) | 8.3 (72 reviews) | 

#### Platform

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Custom Tracking Domain** | 8.2 (210 reviews) | 9.2 (86 reviews) | 
| **Multiple Domains** | 8.2 (205 reviews) | 8.8 (71 reviews) | 
| **Dedicated IP** | 7.9 (200 reviews) | 8.6 (74 reviews) | 
| **Documentation** | 8.2 (240 reviews) ✓ Verified | 8.4 (118 reviews) | 
| **Sender Reputation Management** | 7.8 (218 reviews) | 8.3 (109 reviews) | 
| **Tracking & Reporting** | 8.2 (244 reviews) | 8.3 (121 reviews) | 
| **Enterprise Scalability** | 7.9 (216 reviews) | 8.6 (87 reviews) | 
| **Performance and Reliability** | 8.8 (240 reviews) | 8.7 (126 reviews) | 

### Email Deliverability

| Product | Score | Reviews |
|---|---|---|
| **Customer.io** | N/A | N/A |
| **Twilio SendGrid Email API** | 8.4/10 | 145 |

#### Diagnosis

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **IP Address ** | Not enough data | 8.3 (97 reviews) | 
| **Domains** | Not enough data | 8.8 (105 reviews) | 
| **Content ** | Not enough data | 8.5 (99 reviews) | 
| **Policy Compliance** | Not enough data | 8.7 (98 reviews) | 

#### Tracking

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Processing Time** | Not enough data | 8.9 (116 reviews) | 
| **Placement ** | Not enough data | 8.3 (102 reviews) | 
| **Open Rate** | Not enough data | 8.6 (117 reviews) | 
| **Time to Open** | Not enough data | 8.5 (108 reviews) | 
| **Alerts** | Not enough data | 8.4 (103 reviews) | 

#### Reporting

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Campaign Performance** | Not enough data | 8.3 (98 reviews) | 
| **Domain Reputation** | Not enough data | 8.1 (110 reviews) | 
| **Brand Reputation** | Not enough data | 8.3 (95 reviews) | 
| **Blacklist and Whitelist** | Not enough data | 8.0 (109 reviews) | 

#### Agentic AI - Email Deliverability

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Autonomous Task Execution** | Not enough data | 8.1 (7 reviews) | 
| **Cross-system Integration** | Not enough data | 8.9 (6 reviews) | 
| **Adaptive Learning** | Not enough data | Not enough data | 
| **Proactive Assistance** | Not enough data | Not enough data | 
| **Decision Making** | Not enough data | Not enough data | 

### Push Notification

| Product | Score | Reviews |
|---|---|---|
| **Customer.io** | 8.1/10 | 125 |
| **Twilio SendGrid Email API** | N/A | N/A |

#### Campaigns

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Customize** | 8.6 (114 reviews) | Not enough data | 
| **Scheduling** | 8.7 (111 reviews) | Not enough data | 
| **Retarget** | 8.3 (106 reviews) | Not enough data | 
| **Segmentation** | 8.8 (119 reviews) | Not enough data | 
| **Triggered Notifications** | 8.8 (113 reviews) | Not enough data | 

#### Analytics

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Campaign Performance** | 8.3 (115 reviews) | Not enough data | 
| **Audience Insights** | 7.6 (106 reviews) | Not enough data | 

#### Optimization

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **A/B Testing** | 8.5 (111 reviews) | Not enough data | 
| **Personalization** | 8.8 (113 reviews) | Not enough data | 
| **Rich Notifications** | 8.0 (109 reviews) | Not enough data | 
| **Integrations** | 8.5 (113 reviews) | Not enough data | 

#### Agentic AI - Push Notification

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Autonomous Task Execution** | 6.4 (14 reviews) | Not enough data | 
| **Adaptive Learning** | 6.9 (14 reviews) | Not enough data | 
| **Proactive Assistance** | 6.5 (14 reviews) | Not enough data | 

### SMS Marketing

| Product | Score | Reviews |
|---|---|---|
| **Customer.io** | 7.4/10 | 95 |
| **Twilio SendGrid Email API** | N/A | N/A |

#### Text Messaging

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Bulk SMS** | 8.5 (85 reviews) | Not enough data | 
| **Two-Way Text Messaging** | Feature Not Available | Not enough data | 
| **Text Scheduler** | 8.3 (79 reviews) | Not enough data | 
| **Automatic Replies** | Feature Not Available | Not enough data | 
| **Automatic URL Shortening** | 6.8 (74 reviews) | Not enough data | 
| **MMS Marketing** | 6.5 (76 reviews) | Not enough data | 
| **Personalization** | 8.7 (86 reviews) | Not enough data | 
| **Transactional SMS** | 8.2 (78 reviews) | Not enough data | 

#### SMS Platform

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Reporting** | 7.5 (81 reviews) | Not enough data | 
| **Automation** | 8.3 (84 reviews) | Not enough data | 
| **White Label** | 7.2 (72 reviews) | Not enough data | 
| **Text-to-Landline** | 6.2 (70 reviews) | Not enough data | 
| **Short Codes** | 6.7 (70 reviews) | Not enough data | 
| **API Integration** | 8.3 (82 reviews) | Not enough data | 

#### Agentic AI - SMS Marketing

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Autonomous Task Execution** | 6.4 (17 reviews) | Not enough data | 
| **Multi-step Planning** | 6.4 (17 reviews) | Not enough data | 
| **Cross-system Integration** | 7.5 (17 reviews) | Not enough data | 
| **Natural Language Interaction** | 7.2 (17 reviews) | Not enough data | 
| **Proactive Assistance** | 7.0 (17 reviews) | Not enough data | 
| **Decision Making** | 6.7 (18 reviews) | Not enough data | 

### Customer Data Platform (CDP)

| Product | Score | Reviews |
|---|---|---|
| **Customer.io** | 7.1/10 | 101 |
| **Twilio SendGrid Email API** | N/A | N/A |

#### Data Sourcing

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Data Enrichment** | 7.5 (91 reviews) | Not enough data | 
| **Expandability** | 7.7 (93 reviews) | Not enough data | 
| **Content Marketing** | 7.3 (95 reviews) | Not enough data | 
| **Multiple Devices** | 8.2 (93 reviews) | Not enough data | 

#### Intelligence

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Marketing Metrics** | 7.3 (89 reviews) | Not enough data | 
| **Predictive Modeling** | 5.8 (87 reviews) | Not enough data | 
| **Recommendation Engine** | 5.8 (85 reviews) | Not enough data | 

### Personalization

| Product | Score | Reviews |
|---|---|---|
| **Customer.io** | 5.7/10 | 35 |
| **Twilio SendGrid Email API** | N/A | N/A |

#### Agentic AI - Personalization

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Autonomous Task Execution** | 5.5 (33 reviews) | Not enough data | 
| **Cross-system Integration** | 6.3 (33 reviews) | Not enough data | 
| **Adaptive Learning** | 5.7 (32 reviews) | Not enough data | 
| **Natural Language Interaction** | 5.7 (32 reviews) | Not enough data | 
| **Proactive Assistance** | 5.4 (32 reviews) | Not enough data | 
| **Decision Making** | 5.5 (33 reviews) | Not enough data | 

### Mobile Marketing

| Product | Score | Reviews |
|---|---|---|
| **Customer.io** | 7.4/10 | 80 |
| **Twilio SendGrid Email API** | N/A | N/A |

#### Analysis

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Application Attribution** | Feature Not Available | Not enough data | 
| **Campaign Analysis** | 8.0 (69 reviews) | Not enough data | 
| **Uninstall Tracking** | 6.3 (56 reviews) | Not enough data | 
| **Custom Dashboards** | Feature Not Available | Not enough data | 

#### Campaigns

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Proximity Marketing** | 7.3 (56 reviews) | Not enough data | 
| **Push Notifications** | 8.1 (64 reviews) | Not enough data | 
| **Bulk SMS** | 7.4 (63 reviews) | Not enough data | 
| **Two-Way Text Messaging** | Feature Not Available | Not enough data | 
| **Email Campaigns** | 9.3 (71 reviews) | Not enough data | 
| **Audience Segmentation** | 9.2 (71 reviews) | Not enough data | 

#### Engagement

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Coupons and Promotions** | 6.9 (54 reviews) | Not enough data | 

#### Platform

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Optimization** | 8.0 (61 reviews) | Not enough data | 
| **Integrations - Mobile Marketing** | Feature Not Available | Not enough data | 
| **Internationalization** | 7.6 (59 reviews) | Not enough data | 

#### Agentic AI - Mobile Marketing

| Feature | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Autonomous Task Execution** | 6.7 (6 reviews) | Not enough data | 
| **Multi-step Planning** | 7.6 (7 reviews) | Not enough data | 
| **Cross-system Integration** | 6.1 (6 reviews) | Not enough data | 
| **Adaptive Learning** | 7.1 (7 reviews) | Not enough data | 
| **Proactive Assistance** | 6.9 (7 reviews) | Not enough data | 
| **Decision Making** | 6.9 (6 reviews) | Not enough data | 

---
## Categories
**Shared Categories (1):** [Transactional Email Software](https://www.g2.com/categories/transactional-email)

**Unique to Customer.io (6):** [SMS Marketing Software](https://www.g2.com/categories/sms-marketing), [Personalization Software](https://www.g2.com/categories/personalization), [Push Notification Software](https://www.g2.com/categories/push-notification), [Mobile Marketing Software](https://www.g2.com/categories/mobile-marketing), [Marketing Automation Software](https://www.g2.com/categories/marketing-automation), [Customer Data Platforms (CDP)](https://www.g2.com/categories/customer-data-platform-cdp)

**Unique to Twilio SendGrid Email API (1):** [Email Deliverability Tools](https://www.g2.com/categories/email-deliverability)


---
## Reviewer Demographics

### By Company Size

| Segment | Customer.io | Twilio SendGrid Email API | 
|---|---|---|
| **Small-Business** | 58.5% | 68.3% | 
| **Mid-Market** | 38.0% | 25.3% | 
| **Enterprise** | 3.4% | 6.5% | 

### By Industry

#### Customer.io

- **Computer Software:** 14.7%
- **Financial Services:** 13.3%
- **Information Technology and Services:** 9.0%
- **Marketing and Advertising:** 8.1%
- **Health, Wellness and Fitness:** 5.2%
- **Hospital & Health Care:** 2.5%
- **Internet:** 2.4%
- **Gambling & Casinos:** 2.4%
- **Consumer Services:** 2.4%
- **Insurance:** 2.1%
- **Other:** 37.8%

#### Twilio SendGrid Email API

- **Computer Software:** 17.7%
- **Information Technology and Services:** 13.5%
- **Marketing and Advertising:** 8.4%
- **Internet:** 7.0%
- **Financial Services:** 5.9%
- **Education Management:** 3.1%
- **Non-Profit Organization Management:** 2.5%
- **Retail:** 2.5%
- **Health, Wellness and Fitness:** 2.2%
- **Construction:** 2.2%
- **Other:** 34.8%

---
## Alternatives

### Alternatives to Customer.io

- [Iterable](https://www.g2.com/products/iterable/reviews) — 4.4/5 stars (824 reviews)
- [Braze](https://www.g2.com/products/braze/reviews) — 4.5/5 stars (1680 reviews)
- [Klaviyo](https://www.g2.com/products/klaviyo/reviews) — 4.6/5 stars (1351 reviews)
- [OneSignal](https://www.g2.com/products/onesignal/reviews) — 4.7/5 stars (1184 reviews)
- [Insider One](https://www.g2.com/products/insider-one/reviews) — 4.8/5 stars (1357 reviews)
- [CleverTap](https://www.g2.com/products/clevertap/reviews) — 4.6/5 stars (653 reviews)
- [Bloomreach](https://www.g2.com/products/bloomreach-bloomreach/reviews) — 4.6/5 stars (764 reviews)
- [ActiveCampaign](https://www.g2.com/products/activecampaign/reviews) — 4.4/5 stars (14689 reviews)
- [MoEngage](https://www.g2.com/products/moengage/reviews) — 4.5/5 stars (524 reviews)
- [WebEngage](https://www.g2.com/products/webengage/reviews) — 4.5/5 stars (751 reviews)

### Alternatives to Twilio SendGrid Email API

- [Intuit Mailchimp Email Marketing](https://www.g2.com/products/intuit-mailchimp-email-marketing/reviews) — 4.3/5 stars (12964 reviews)
- [Brevo Marketing Platform](https://www.g2.com/products/brevo-marketing-platform/reviews) — 4.5/5 stars (2563 reviews)
- [Netcore Email API](https://www.g2.com/products/netcore-email-api/reviews) — 4.4/5 stars (732 reviews)
- [Mailgun](https://www.g2.com/products/mailgun/reviews) — 4.2/5 stars (321 reviews)
- [SparkPost](https://www.g2.com/products/sparkpost/reviews) — 4.0/5 stars (73 reviews)
- [SendPulse](https://www.g2.com/products/sendpulse/reviews) — 4.6/5 stars (713 reviews)
- [SocketLabs](https://www.g2.com/products/socketlabs/reviews) — 4.5/5 stars (41 reviews)
- [SMTP2GO](https://www.g2.com/products/smtp2go/reviews) — 4.7/5 stars (226 reviews)
- [Elastic Email](https://www.g2.com/products/elastic-email/reviews) — 4.4/5 stars (212 reviews)
- [Amazon Simple Email Service (Amazon SES)](https://www.g2.com/products/amazon-simple-email-service-amazon-ses/reviews) — 4.3/5 stars (202 reviews)

---
## Top Discussions

### Customer.io

- Title: [What is Customer.io used for?](https://www.g2.com/discussions/what-is-customer-io-used-for) — 2 comments
  > **Top comment:** "customer.io is an incredibly feature-packed combination of user messaging services into one platform."
- Title: [Is it available in Bangladesh?](https://www.g2.com/discussions/is-it-available-in-bangladesh) — 1 comment, 2 upvotes
  > **Top comment:** "Visit ClimaxRecovery or send an email to info@climaxrecovery.com +1 909 248 4443
Provide all necessary information
Recovery process starts, and your..."
- Title: [What is the best way to make automations a smoother process?](https://www.g2.com/discussions/what-is-the-best-way-to-make-automations-a-smoother-process) — 1 comment, 1 upvote
  > **Top comment:** "Start small workflows. Make use of the content that your marketing and sales teams have. Use Goals. Know when to unenroll the contacts from the automation..."
- Title: [how is this site for mails?](https://www.g2.com/discussions/36887-how-is-this-site-for-mails) — 1 comment, 1 upvote
  > **Top comment:** "I don't know"

### Twilio SendGrid Email API

- Title: [What is my API Key?](https://www.g2.com/discussions/api-key-5793c785-2bfd-4896-a233-92f65c2f8462) — 1 comment, 1 upvote *(includes official response)*
  > **Top comment:** "Your API key is the same string as the password that you use to log onto sendgrid.com. Don't forget that you can also create auxiliary sets of API..."
- Title: [Can I send from more than one domain through SendGrid?](https://www.g2.com/discussions/sending-from-multiple-domains) — 1 comment, 1 upvote *(includes official response)*
  > **Top comment:** "Depending on your account level, this can be accomplished. If you are sending through a shared IP plan then no additional changes are required and you can..."

---
**Source:** [G2.com](https://www.g2.com) | [Comparison Page](https://www.g2.com/compare/customer-io-vs-twilio-sendgrid-email-api)