A man has been arrested in Brighton after a string of abusive emails were sent to deputy Labour leader Angela Rayner.
Police say they have arrested a 68-year-old was on suspicion of malicious communications as part of an investigation into emails sent on 17 November.
Greater Manchester Police say he has since been released on bail.
Officers say four people have been arrested so far as part of the investigation, resulting in one man being charged and sentenced in connection.
A spokesman for Ms Rayner confirmed the arrest announced by Greater Manchester Police related to her, adding: "We are working with the police to ensure that the perpetrators of these crimes are brought to justice and Angela would like to thank the police for their work during these investigations.
"Abuse and threats of this nature don't just have an impact on Angela but also on her family, her children and her staff, who are on the receiving end of these communications."
Anyone with information should contact police on 0161 856 9262 via 101 or our LiveChat function at www.gmp.police.uk. Alternatively details can be passed via the anonymous charity Crimestoppers on 0800 555 111.
If you have been a victim of hate, don't suffer in silence. Visit gmvictims.org.uk to access victim support and information. You can report hate crime online, via www.gmp.police.uk or by calling 101.